void del_all(LNode *L)
{

	while (L -> next != NULL)
	{
		LNode *p = L -> next;
		LNode *minp = L ->next;
		LNode *pre = L;
		LNode *minpre = pre;

		while (p -> next != L)
		{
			if (p -> data < minp -> data)
			{
				minpre = pre;
				minp = p;
				pre = p;
				p = p -> next;
			}

			pre = p;
			p = p -> next;
		}

		minpre -> next = minp -> next;
		free(minp);
	}

	free(L);
}